• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Depletion mode mosfets for 2mA CCS ?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Does anyone know of a depletion mode mosfet suitable for use in a 2mA ccs capable of handling 350V ?

I have use the LND150 very successfully for currents < 1mA, and the DN2540 / IXCP10M45s for currents > 7mA.

1mA appears to be the upper limit for the LND150.

The DN2540 datasheet indicates that gm is miniscule at 2mA, implying low effective resistance.

Althought the IXCP10M45 datasheet implies an operational current bandwith commencing at 2mA, I suspect that effective gm will also be very low at this current.

ideas / comments ?
 
Thanks guys,

I have used the DN3545 before as the lower element in a cascode with the DN2540. Surprisingly, it has a very similar current v transconductance characteristics to the DN2540 (ie it is also miniscule at 2mA), which pretty well rules it out in terms of the resultant ccs effective resistance.

The paralleling of LND150 sounds like a great idea (why didn't I think of it?) which I will definitely trial.
 
From AN-D16 -- when I simulate it, I get no distortion -- wassup?
 

Attachments

  • depletion.gif
    depletion.gif
    9.3 KB · Views: 816
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.